Provided are vesicles derived from bacteria belonging to the genus Micrococcus, a composition and a use thereof, wherein the vesicles and the composition comprising the same may be effectively used for the development of a method of diagnosing gastric cancer, pancreatic cancer, cholangiocarcinoma, breast cancer, ovarian cancer, bladder cancer, myocardial infarction, cardiomyopathy, atrial fibrillation, variant angina, chronic obstructive pulmonary disease (COPD), dementia, or diabetes.
